A hybrid vehicle including a converter for stepping up an output voltage of a battery is known. The voltage stepped up by the converter is further converted by an inverter to an AC voltage and applied to a motor generator. When the hybrid vehicle is regeneratively braked, a voltage of electric power generated by the motor generator can also be stepped down by means of the converter to a voltage which is appropriate for charging the battery. Such a converter is required to reduce an electric power loss due to switching.
For example, a control device of a load drive system disclosed in Japanese Patent Laying-Open No. 2010-283932 (PTL 1) corrects a command value so that an absolute value of a difference between the command value and an output voltage of the converter is reduced, when an absolute value of load power is less than a predetermined value. This control device enables an output voltage of the converter to be kept even when the converter is halted. Therefore, in the case where it is unnecessary to change the output voltage, the converter can be halted. Accordingly, an electric power loss of the converter can be reduced.